move to new System.Threading.Lock type for better performance

Emby.Server.Implementations/EntryPoints/LibraryChangedNotifier.cs

@@ -34,7 +34,7 @@ public sealed class LibraryChangedNotifier : IHostedService, IDisposable
     private readonly IUserManager _userManager;
     private readonly ILogger<LibraryChangedNotifier> _logger;
 
-    private readonly object _libraryChangedSyncLock = new();
+    private readonly Lock _libraryChangedSyncLock = new();
     private readonly List<Folder> _foldersAddedTo = new();
     private readonly List<Folder> _foldersRemovedFrom = new();
     private readonly List<BaseItem> _itemsAdded = new();

Emby.Server.Implementations/EntryPoints/UserDataChangeNotifier.cs

@@ -24,7 +24,7 @@ namespace Emby.Server.Implementations.EntryPoints
         private readonly IUserManager _userManager;
 
         private readonly Dictionary<Guid, List<BaseItem>> _changedItems = new();
-        private readonly object _syncLock = new();
+        private readonly Lock _syncLock = new();
 
         private Timer? _updateTimer;